> you mean add the call site to the expected_arguments list, slightly confused because you've put this next to the negative case that doesn't filter by arguments. I assume you only want this to happen on the ones that do args matching?

No, I would like an additional spec added specifically for this.  Having a spec for it calls it out as important (which it is).

> Based on looking at this I'd assume we have tests elsewhere for call sites from CallerFilter


No, setting a mock expectation on `CallerFilter` doesn't really help us here; consider that a few weeks back, we had two different deprecation warnings that were printing the wrong call site, and both were using the `CallerFilter`  (or the equivalent, before that got added):

* in rspec-expectations, the `be_true` deprecation was printing a line from `rspec/matchers.rb`, because the caller-searching logic considered `rspec/matchers/*.rb` to be an rspec file but not `rspec/matchers.rb`.  Luckily, `CallerFilter` as added to rspec-mocks already handled this correctly, so I ported it to rspec-core to solve the bug.
* in rspec-mocks, the deprecation for the any_instance receiver yielding was printing a line from the user's code but the wrong line, because we wanted it to print the line where the implementation block was defined, but the warning was triggered when the mocked/stubbed method was called, and thus `CallerFilter` was being given the wrong backtrace to begin with.

To really have confidence that the right line is being printed, we need a spec that actually asserts on the file and line number (typically with `__FILE__` and `__LINE__` so that it won't fail as new code is added to the file or if the file is renamed).  We have a [helper method](https://github.com/rspec/rspec-core/blob/5f0e7a0465dcedd5b26d658be72b8c0ec59a3e5d/spec/support/helper_methods.rb#L26-L30) in rspec-core that assists with testing this.  I recommend porting that to here (eventually, I suspect it'll go into the `rspec-support` gem we've discussed) and then you can test this like so:

``` ruby
it "includes the call site in the deprecation warning" do
  obj = Object.new
  expect_deprecation_with_call_site(__FILE__, __LINE__ + 1)
  obj.stub(:faces)
end
```

Does that make sense?